Semiconductor component having a diode structure in a sic semiconductor body

ABSTRACT

A semiconductor component includes a semiconductor component, including: a merged PiN Schottky (MPS) diode structure in a SiC semiconductor body having a drift zone of a first conductivity type; an injection region of a second conductivity type adjoining a first surface of the SiC semiconductor body; a contact structure at the first surface, the contact structure forming a Schottky contact with the drift zone and electrically contacting the injection region; and a zone of the first conductivity type formed between the injection region and a second surface of the SiC semiconductor body, the second surface being situated opposite the first surface. The zone is at a maximal distance of 1 μm from the injection region of the second conductivity type.

TECHNICAL FIELD

The present application relates to SiC (silicon carbide) semiconductorcomponents, for example semiconductor switches having a low onresistance and a high dielectric strength.

BACKGROUND

In semiconductor components having field effect transistor structuresand a drift zone, pn junctions between the drift zone and body regionsof the field effect transistors form an intrinsic body diode. If thebody diode is operated in the forward direction, then a bipolar chargecarrier flow through the body regions and the drift zone is established.Electrical properties of the body diode, such as e.g. threshold voltage,forward voltage and current-carrying capacity, result from the dopingand the dimensions of doped regions at semiconductor/metal junctions,which are in turn defined with regard to the transistor propertiessought.

It is generally endeavoured to improve properties such as the avalancherobustness, the breakdown strength and the on resistance of components.

SUMMARY

The present disclosure relates to a semiconductor component comprising afield effect transistor structure in a SiC semiconductor body having agate structure at a first surface of the SiC semiconductor body and adrift zone of a first conductivity type. A zone of the firstconductivity type is formed in a vertical direction between asemiconductor region of a second conductivity type and the drift zone.The zone is spaced apart from the gate structure and is at a maximaldistance of 1 μm from the semiconductor region in the verticaldirection.

The present disclosure additionally relates to a semiconductor componentcomprising a Merged Pin Schottky, MPS, diode structure in a SiCsemiconductor body having a drift zone of a first conductivity type. Aninjection region of a second conductivity type adjoins a first surfaceof the SiC semiconductor body. A contact structure at the first surfaceforms a Schottky contact with the drift zone and electrically contactsthe injection region. A zone of the first conductivity type is formedbetween the injection region and a second surface of the SiCsemiconductor body, said second surface being situated opposite thefirst surface. The zone is at a maximal distance of 1 μm from theinjection region of the second conductivity type.

The present disclosure furthermore relates to a semiconductor componentcomprising a pn diode structure in a SiC semiconductor body having adrift zone of a first conductivity type. An injection region of a secondconductivity type adjoins a first surface of the SiC semiconductor body.A contact structure at the first surface electrically contacts theinjection region. A zone of the first conductivity type is formedbetween the injection region and a second surface of the SiCsemiconductor body, said second surface being situated opposite thefirst surface. The zone is electrically isolated from the contactstructure at the first surface and is at a maximal distance of 1 μm fromthe injection region of the second conductivity type.

The present disclosure additionally relates to a semiconductor componentcomprising a SiC semiconductor body having a drift zone of a firstconductivity type. A doped region of a second conductivity type isformed between a first surface of the SiC semiconductor body and thedrift zone. A recombination zone having recombination centres composedof lattice defects and/or heavy metal atoms is formed between the dopedregion and a second surface situated opposite the first surface. Afurther recombination zone having recombination centres composed oflattice defects and/or heavy metal atoms, said further recombinationzone being spaced apart from the recombination zone, is formed betweenthe doped region and the recombination zone or in the doped region andis formed at a maximum distance of 1 μm from the drift zone.

Further features and advantages of the disclosed subject matter willbecome apparent to the person skilled in the art upon reading thefollowing detailed description and upon consideration of the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings convey a deeper understanding of exemplaryembodiments of a semiconductor component and of a method for producing asemiconductor component, are included in the disclosure and form a partthereof. The drawings merely illustrate embodiments and together withthe invention serve to elucidate the principles thereof. Thesemiconductor component described herein, and the method describedherein are therefore not restricted to the exemplary embodiments by thedescription thereof. Further exemplary embodiments and intendedadvantages emerge from the understanding of the following detaileddescription and also from combinations of the exemplary embodimentsdescribed below, even if they are not explicitly described. The elementsand structures shown in the drawings are not necessarily illustrated astrue to scale with respect to one another. Identical reference signsrefer to identical or mutually corresponding elements and structures.

FIG. 1 is a schematic vertical cross section through a section of a SiCsemiconductor component comprising an intrinsic body diode having areduced emitter efficiency in accordance with one embodiment comprisinga zone of the conductivity type of the drift zone between the bodyregions and the drift zone.

FIG. 2A is a schematic horizontal cross section through a section of aSiC semiconductor component in accordance with one embodiment comprisingstrip-like field effect transistor structures and comprising zones forreducing the emitter efficiency of an intrinsic body diode, wherein thezones are aligned with semiconductor regions of the conductivity type ofbody regions.

FIG. 2B is a schematic vertical cross section through the section of theSiC semiconductor component according to FIG. 2A along thecross-sectional line B-B′.

FIG. 3A is a schematic vertical cross section through a section of a SiCsemiconductor component in accordance with one embodiment comprisingplanar gate structures and comprising zones aligned with body regionsfor reducing the emitter efficiency of an intrinsic body diode.

FIG. 3B is a schematic vertical cross section through a section of a SiCsemiconductor component in accordance with one embodiment comprisingshallow gate structures and comprising zones aligned with body regionsfor reducing the emitter efficiency of an intrinsic body diode.

FIG. 3C is a schematic vertical cross section through a section of a SiCsemiconductor component in accordance with one embodiment comprisingdeep gate structures, deep contact trenches and comprising zones alignedwith diode terminal regions for reducing the emitter efficiency of anintrinsic body diode.

FIG. 4 is a schematic vertical cross section through a section of a SiCsemiconductor component in accordance with one embodiment comprisingdeep gate structures and comprising a continuous zone of theconductivity type of the drift zone for reducing the emitter efficiencyof an intrinsic body diode.

FIG. 5 is a schematic vertical cross section through a section of a SiCsemiconductor component in accordance with one embodiment comprisingdeep gate structures and comprising a continuous zone—spaced apart fromsemiconductor regions of the conductivity type of body regions—of theconductivity type of the drift zone for reducing the emitter efficiencyof an intrinsic body diode.

FIG. 6A is a schematic horizontal cross section through a SiCsemiconductor component in accordance with one embodiment comprising acontinuous zone extending over a cell array region for reducing theemitter efficiency of an intrinsic body diode.

FIG. 6B is a schematic horizontal cross section through a SiCsemiconductor component in accordance with one embodiment comprising amultiplicity of mutually separated zones aligned with semiconductorregions of the conductivity type of body regions for reducing theemitter efficiency of an intrinsic body diode.

FIG. 7 is a simplified diagram for illustrating the temperature responseof the emitter efficiency of an intrinsic body diode for elucidating theembodiments.

FIG. 8A is a schematic horizontal cross section through a section of aSiC semiconductor component comprising strip-like field effecttransistor structures in accordance with one embodiment comprising moreweakly doped zones of the conductivity type of the body regions, saidzones being formed along a cell longitudinal axis and being separatedfrom one another.

FIG. 8B is a schematic vertical cross section through the section of theSiC semiconductor component according to FIG. 8A along thecross-sectional line B-B′.

FIG. 9A is a schematic vertical cross section through a section of a SiCsemiconductor component in accordance with one embodiment comprising azone for reducing the emitter efficiency of an intrinsic body diode anda continuous recombination zone near the rear side of the component.

FIG. 9B is a schematic vertical cross section through a section of a SiCsemiconductor component comprising a zone for reducing the emitterefficiency of an intrinsic body diode in accordance with one embodimentcomprising recombination zones near the rear side of the component andthe front side of the component.

FIG. 9C is a schematic vertical cross section through a section of a SiCsemiconductor component in accordance with one embodiment comprisingrecombination zones near the rear side of the component and the frontside of the component.

FIG. 10A is a schematic vertical cross section through a section of aSiC semiconductor component comprising zones for reducing the emitterefficiency in accordance with one embodiment concerning semiconductorcomponents comprising a pn diode structure, wherein the zones adjoin aninjection region.

FIG. 10B is a schematic vertical cross section through a section of aSiC semiconductor component comprising a zone for reducing the emitterefficiency in accordance with one embodiment concerning semiconductorcomponents comprising a pn diode structure, wherein the zone is formedat a distance from the injection region.

FIG. 11A is a schematic vertical cross section through a section of aSiC semiconductor component comprising zones for reducing the emitterefficiency in accordance with one embodiment concerning semiconductorcomponents comprising an MPS diode structure, wherein the zones adjoininjection regions.

FIG. 11B is a schematic vertical cross section through a section of aSiC semiconductor component comprising a zone for reducing the emitterefficiency in accordance with one embodiment concerning semiconductorcomponents comprising an MPS diode structure, wherein the zone is formedat a distance from injection regions.

FIG. 12A is a schematic flow diagram for a method for producing asemiconductor component in accordance with one embodiment concerningsemiconductor components comprising a field effect transistor structure.

FIG. 12B is a schematic flow diagram for a method for producing asemiconductor component in accordance with one embodiment concerningsemiconductor components comprising a fine pn diode structure.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings, which form part of the disclosure and showspecific exemplary embodiments of a semiconductor component and of amethod for producing a semiconductor component for illustrationpurposes. It goes without saying that further exemplary embodimentsexist. It likewise goes without saying that structural and/or logicalchanges can be made to the exemplary embodiments, without in so doingdeparting from what is defined by the patent claims. The description ofthe exemplary embodiments is non-limiting in this respect. Inparticular, features of exemplary embodiments described below can becombined with features of others of the exemplary embodiments described,provided that nothing to the contrary is evident from the context.

The terms “have”, “contain”, “encompass”, “comprise” and similar termsare open terms and indicate the presence of the stated structures,elements or features, but do not exclude the presence of additionalelements or features. The indefinite articles and the definite articlesare intended to encompass both the plural and the singular, unlesssomething to the contrary is clearly evident from the context.

The term “electrically connected” describes a permanent low-impedanceconnection between electrically connected elements, for example a directcontact between the relevant elements or a low-impedance connection viaa metal and/or a highly doped semiconductor. The term “electricallycoupled” encompasses the fact that one or more intervening elementssuitable for signal transmission can be present between the electricallycoupled elements, for example elements which provide at times, in afirst state, a low-impedance connection and, in a second state, ahigh-impedance electrical decoupling.

The figures illustrate relative doping concentrations by the signs of“−” or “+” next to the doping type “n” or “p”. By way of example, “n⁻”indicates a doping concentration which is lower than the dopingconcentration of an “n”-type doping region, while in an “n⁺”-type dopingregion the doping concentration is higher than in an “n”-type dopingregion. Doping regions of the same relative doping concentration do notnecessarily have the same absolute doping concentration. By way ofexample, two different “n”-type doping regions can have the same dopingconcentration or different absolute doping concentrations. The term“dopant concentration” denotes a net dopant concentration, provided thatnothing to the contrary is evident from the context.

The expression “electrical connected” describes a low-impedanceconnection between the electrically connected elements, for example adirect contact between the relevant elements or a connection via a metaland/or a highly doped semiconductor. The expression “electricallycoupled” includes the fact that one or more intervening elementssuitable for signal transmission can be present between the“electrically coupled” elements, e.g. elements which are controllablesuch that they can produce at times a low-impedance connection in afirst state and a high-impedance decoupling in a second state.

If a value range with the indication of one limit value or two limitvalues is defined for a physical variable, then the propositions “from”and “to” or “less” and “more” include the respective limit value. Anindication of the type “from . . . to” is accordingly understood as“from at least . . . to at most”. Correspondingly, an indication of thetype “less . . . ” (“more . . . ”) is understood as “at most . . . ”(“at least . . . ”).

FIG. 1 shows a semiconductor component 500, which can be for example anIGFET (insulated gate field effect transistor), for example a MOSFET(metal oxide semiconductor FET), wherein the abbreviation MOSFETencompasses both FETs having a metallic gate electrode and FETs havingsemiconductor gate electrodes, a semiconductor diode, e.g. a pn diode oran MPS (merged pin Schottky) diode, an IGBT (insulated gate bipolartransistor) or an MCD (MOS-controlled diode).

The semiconductor component 500 is based on a semiconductor body 100formed with silicon carbide. By way of example, the semiconductor body100 comprises or consists of a silicon carbide crystal, wherein thesilicon carbide crystal can comprise doping atoms and/or impurities,e.g. hydrogen and/or oxygen atoms, besides the main constituents ofsilicon and carbon. The polytype of the silicon carbide crystal can befor example 2H, 6H, 15R or 4H.

A first surface 101 on the front side of the SiC semiconductor body 100is planar or ribbed. A normal 104 to a planar first surface 101 or to acentral plane of a ribbed first surface 101 defines a verticaldirection. Directions parallel to a planar first surface 101 or to thecentral plane of a ribbed first surface 101 are horizontal and lateraldirections.

There is formed in the SiC semiconductor body 100 a field effecttransistor structure having a gate structure 150 at a first surface 101of the SiC semiconductor body 100 and a drift zone 131 of a firstconductivity type. A zone 133 of the first conductivity type can beformed in the vertical direction between a semiconductor region 120, 160of a second conductivity type and the drift zone 131, which zone of thefirst conductivity type can be spaced apart from the gate structure 150and can be at a maximal distance of 1 μm from the semiconductor region120, 160 in the vertical direction. It is possible for the zone 133 todirectly adjoin the semiconductor region 120, 160.

By way of example, the field effect transistor structure comprises atransistor cell TC on the front side of the SiC semiconductor body 100.The transistor cell TC can comprise a source region 110 of the firstconductivity type, which can be electrically connected to a first loadterminal L1 of the semiconductor component 500. The transistor cell TCcan be a lateral transistor cell having a planar gate structure 150formed on the first surface 101, or a vertical transistor cell having agate structure 150 formed in a trench. The gate structure 150 cancomprise a gate electrode 155, which is electrically connected to a gateterminal G of the semiconductor component 500.

The semiconductor region 120, 160 of the second conductivity type formedbetween the first surface 101 and the drift structure 130 can comprisefor example a body region 120 of the transistor cell TC and/or a dioderegion 160. The semiconductor region 120, 160 can be connected to thefirst load terminal L1. By way of example, the semiconductor region 120,160 can extend as far as a contact at the first surface.

The drift zone 131 can be part of a drift structure 130 formed betweenthe transistor cell TC and a second surface 102 on the rear side of theSiC semiconductor body 100, said second surface being situated oppositethe first surface 101. The drift structure 130 can comprise a highlydoped contact layer 139 extending directly along the second surface 102.The highly doped contact layer 139 is electrically connected to a secondload terminal L2 of the semiconductor component 500. A vertical extentof the contact layer 139 can be more than 50 μm, e.g. more than 100 μm.The weakly doped drift zone 131 is formed between the transistor cellsTC and the highly doped contact layer 139.

First pn junctions pn1 between the semiconductor regions 120, 160 andthe drift structure 130 form at least sections of an intrinsic bodydiode BD of the semiconductor component 500.

If the intrinsic body diode BD is turned off, then a gate potentialapplied to the gate terminal G controls a unipolar charge carrier flowthrough the body regions 120 of the transistor cells TC. If theintrinsic body diode BD is forward-biased, a bipolar charge carrier flowof holes and electrons can be established between the semiconductorregion 120, 160 and the drift structure 130, provided that thetransistor channel is completely closed and/or the current in theforward direction exceeds a threshold value.

The embodiments described below concern the lowering of the emitterefficiency of the intrinsic body diode BD on the part of thesemiconductor regions 120, 160, i.e., in the case of p-dopedsemiconductor regions 120, 160, the anode emitter efficiency. The anodeemitter efficiency γ_(Anode) is a measure of the hole current injectedinto the weakly doped drift zone 131. By way of example, the contactresistance of a metal-semiconductor junction between the first loadterminal L1 and the semiconductor region 120, 160 and also the absolutevalue and profile of the dopant concentrations at the pn junction pninfluence the anode emitter efficiency γ_(Anode).

The zone 133 of the conductivity type of the drift zone 131, said zonebeing formed between the semiconductor region 120, 160 and the driftzone 131, has a dopant concentration that is at least double themagnitude of that in sections of the drift zone 131 which adjoin thezone 133. By way of example, a maximum dopant concentration in the zone133 is at least double the magnitude of, e.g. five times higher than, aminimum dopant concentration in the drift zone 131. At the location ofthe maximum dopant concentration, the zone 133 can be partly compensatedwith dopants of the second conductivity type. The dopant dose of thezone 133 can lie in a range of from 5% to 20% of the breakdown charge ofSiC.

The zone 133 can be at least partly doped with at least one dopanthaving a deep energy level with a gap of at least 150 meV with respectto the closest band edge. Such a dopant is phosphorus, chromium oriridium, for example.

The zone 133 can be at a vertical and/or lateral distance from the gatestructure 150 of the transistor cell TC, such that a unipolar chargecarrier flow that flows through the body region 120 in the on state ofthe transistor cell TC does not directly enter the zone 133.

In accordance with one embodiment, the zone 133 is formed such that noor only a slight proportion of the switch-on current of the transistorcell TC flows through the zone 133. In accordance with anotherembodiment, the switch-on current of the transistor cell TC between thebody region 120 and the zone 133 passes through a current distributionzone of the conductivity type of the drift zone 131, wherein the currentdistribution zone can be directly adjacent to the body region 120 orelse be spaced apart from the latter, takes up the unipolar chargecarrier flow through the body region 120 and distributes it at leastpartly via the zone 133 towards the drift zone 131. In this case, adopant concentration in the current distribution zone is at least doublethe magnitude of that in the drift zone 131, e.g. at least five timesthe magnitude thereof.

The zone 133 can directly adjoin the doped semiconductor region 120, 160or be spaced apart from the latter. A distance between the zone 133 andthe semiconductor region 120, 160 can be for example up to 1 μm forcomponents having a low nominal blocking capability and even up to 3 μmfor components having a higher nominal blocking capability. Thesemiconductor region 120, 160 can extend as far as an electrical contactformed at the first surface 101 of the SiC semiconductor body 100 or canadjoin a trench contact extending into the SiC semiconductor body 100.

The semiconductor region 120, 160 can be the body region 120 or a dioderegion 160. An average dopant concentration in the diode region 160 canbe at least double the magnitude of that in the body region 120.Furthermore, it is possible for the diode region 160 to be directlyadjacent to the body region 120.

The zone 133 can significantly reduce the emitter efficiency and thusalso the hole injection in on-state operation of the intrinsic bodydiode BD. Thus, in forward operation of the intrinsic body diode BD, theplasma flooding of the SiC semiconductor body 100 decreases andsignificantly fewer charge carriers recombine within the drift zone 131.Stacking faults that otherwise propagate in the SiC crystal owing tolocal evolution of heat attributed to the recombination of chargecarriers in the SiC crystal are thus reduced as well. Operation of thebody diode BD can accordingly remain without influence or almost withoutinfluence on the on resistance RDSon of the semiconductor component,which can otherwise rise gradually as a result of the constant newformation of crystal defects during operation of the semiconductorcomponent and lead to unacceptable component degradation.

The intrinsic body diode BD of such a semiconductor component 500 canaccordingly replace an external freewheeling diode, for example, withoutthe operation of the intrinsic body diode BD adversely affecting thelong-term stability of the component properties. In addition, thesteepening of the electric field that is brought about by the zone 133can result in more reliable pinning of the avalanche breakdown withinthe cell array.

A possible slight increase—attributed to the reduced hole injection—inthe forward voltage of the intrinsic body diode BD in the range of frome.g. 1 V to 2 V remains insignificant in applications in which theintrinsic body diode BD is operated in the on state only for acomparatively short time per switching cycle. One such application ise.g. the operation of the intrinsic body diode BD as a freewheelingdiode in a bridge circuit in which the body diode BD is operated in theforward direction only during a dead time in the course of thecommutation of the bridge circuit.

A vertical extent of the zone 133 is relatively small, for examplebetween 50 nm and 1 μm or between 200 nm and 500 nm, such that theinfluence of the zone 133 on the blocking capability of thesemiconductor component 500 can remain small. The dopant dose of thezone 133 can be 5% to 20% of the breakdown charge of the material of theSiC semiconductor body 100, which typically lies between 1 and 2×10¹³cm⁻² depending on the drift zone doping. The entire zone 133 or at leastone vertical section of the zone 133, e.g. in the region of the maximumdopant concentration, can be partly counter-compensated with dopants ofthe second conductivity type. A suitable doping in the zone 133 canlocally steepen and “pin” the electrical field and thus improve theavalanche behaviour of the semiconductor component 500.

In accordance with one embodiment, the dopants in the zone 133 can be orcontain those with a deep energy level in the band gap, for examplephosphorus, chromium and/or iridium. The presence of a dopant with adeep energy level can lead to a pronounced positive temperaturecoefficient of the forward voltage of the body diode since the zone 133thus doped is initially only partly activated at room temperature T0even in the flooded state and the degree of activation can risesignificantly as the temperature increases. The positive temperaturecoefficient of the forward voltage counteracts the rise in the emitterefficiency and also the defect growth linked thereto. Moreover, the zone133 brings about a flattening of the rise in the on resistance RDSon asthe temperature rises.

The charge carrier mobility can moreover be reduced in a section of theSiC semiconductor body 100 that comprises the zone 133. By way ofexample, the zone 133 or a section of the SiC semiconductor body 100that comprises the zone 133 can have a counter-doping, for instancealuminium, boron and/or gallium atoms, which partly compensates theactual n-type doping, for which reason, on the other hand, the n-typedoping must be increased in order to obtain the same net doping.

FIGS. 2A and 2B relate to embodiments of semiconductor components 500comprising a SiC semiconductor body 100 and comprising strip-like gatestructures 150 formed in trenches. For details of the SiC semiconductorbody 100, reference is made to the description concerning FIG. 1.

On a front side, the SiC semiconductor body 100 has a first surface 101,which can comprise coplanar surface sections. The first surface 101 cancoincide with a principal crystal plane or extend at an off-axis angle αobliquely with respect to a principal crystal plane, wherein theoff-axis angle can be at least 2° and at most 12°, e.g. approximately4°.

In the embodiment illustrated, the <0001> crystal axis is inclined by anoff-axis angle α with respect to the normal 104. The <11-20> crystalaxis is inclined by the same off-axis angle with respect to thehorizontal plane. The <1-100> crystal axis is orthogonal to thecross-sectional plane.

On the rear side, the SiC semiconductor body 100 has a second surface102 parallel to the first surface 101. A distance between the firstsurface 101 on the front side and the second surface 102 on the rearside depends on the nominal blocking ability of the semiconductorcomponent 500.

A highly doped contact layer 139 adjoining the second surface 102 of theSiC semiconductor body 100 can be or comprise a substrate section slicedfrom a single crystal. The contact layer 139 forms an ohmic contact witha second load electrode 320, which can directly adjoin the secondsurface 102. Along the second surface 102, the dopant concentration ofthe contact layer 139 is high enough to form an ohmic contact with thesecond load electrode 320.

If the semiconductor component 500 is a MOSFET or if the semiconductorcomponent 500 comprises such a MOSFET, then the contact layer 139 hasthe conductivity type of the drift zone 131. If the semiconductorcomponent 500 is an IGBT, then the contact layer 139 has theconductivity type complementary to that of the drift zone 131 orcomprises zones of both conductivity types.

The drift zone 131 can be formed in a layer grown by epitaxy on thecontact layer 139. An average dopant concentration in the drift zone 131lies for example in a range of from 10¹⁴ cm⁻³ to 5×10¹⁶ cm⁻³. Besidesthe drift zone 131 and the contact layer 139, the drift structure 130can comprise further doped regions, for example field stop zones,blocking and/or barrier zones and/or current distribution zones of theconductivity type of the drift zone 131 and/or insular regions of thecomplementary conductivity type.

The drift zone 131 can directly adjoin the contact layer 139. Inaccordance with one embodiment, the drift zone 131 forms an n⁻/njunction with a buffer layer formed between the drift zone 131 and thecontact layer 139, wherein a vertical extent of the buffer layer can beat least 0.3 μm and maximal 10 μm, e.g. between 0.5 μm and 5 μm, and anaverage dopant concentration in the buffer layer can lie in a range offrom 10¹⁷ cm⁻³ to 3×10¹⁸ cm⁻³ or in a range of from 2×10¹⁷ cm⁻³ to1×10¹⁸ cm⁻³. The buffer layer can reduce mechanical stress in the SiCsemiconductor body 100 and/or influence the electric field in the driftstructure 130 in a predetermined manner.

The transistor cells TC on the front side of the SiC semiconductor body100 are formed along gate structures 150 extending from the firstsurface 101 into the SiC semiconductor body 100, wherein mesa sections190 of the SiC semiconductor body 100 separate adjacent gate structures150 from one another.

A longitudinal extent of the gate structures 150 along a firsthorizontal direction is greater than a width of the gate structures 150along a second horizontal direction orthogonal to the first horizontaldirection and transverse to the longitudinal extent. The gate structures150 can be long trenches extending from one side of a cell array regioncomprising the transistor cells TC as far as an opposite side, whereinthe length of the gate structures 150 can be up to a plurality of 100μm, for example up to a plurality of millimetres.

In accordance with other embodiments, the gate structures 150 can beformed along parallel lines extending in each case from one side of thecell array region to the opposite side, and wherein a multiplicity ofgate structures 150 separated from one another are formed in each casealong the same line. The gate structures 150 can also form a latticewith mesa sections 190 in the meshes of the lattice.

At the underside, the gate structures 150 can be rounded, in particularat a transition from a sidewall of the gate structure 150 to a bottom ofthe gate structure 150. By way of example, a radius of curvature is atleast double the thickness of a gate dielectric 151, described below, inthe gate structures 150.

The gate structures 150 can be uniformly spaced apart from one another,can have the same width and can form a regular pattern, wherein a pitch(centre-to-centre distance) of the gate structures 150 can lie in arange of from 1 μm to 10 μm, e.g. of from 2 μm to 5 μm. A verticalextent of the gate structures 150 can lie in a range of from 300 nm to 3μm, e.g. in a range of from 500 nm to 1 μm.

Sidewalls of the gate structures 150 can be aligned vertically withrespect to the first surface 101 or can be tilted slightly relative tothe vertical direction, wherein opposite sidewalls can extend parallelto one another or towards one another. In accordance with oneembodiment, the width of the gate structures 150 decreases withincreasing distance from the first surface 101. By way of example, theone sidewall deviates from the vertical by approximately the off-axisangle α and the other sidewall by −α.

In accordance with one embodiment, the mesa sections 190 comprise twoopposite longitudinal mesa sidewalls 191, 192, which directly adjoin twoadjacent gate structures 150. At least one first mesa sidewall 191 liesin a principal crystal plane with high charge carrier mobility, e.g. ina {11-20} crystal plane. The second mesa sidewall 192 situated oppositethe first mesa sidewall 191 can be inclined by double the off-axis angleα, for example by approximately 8 degrees, with respect to the relevantprincipal crystal plane.

A conductive gate electrode 155 in the gate structures 150 can comprisea highly doped polycrystalline silicon layer, an integral ormultipartite metal structure or both. The gate electrode 155 can beelectrically connected to a gate metallization 330, which forms a gateterminal G or is electrically connected or coupled to such a gateterminal.

Along at least one side of the gate structure 150, a gate dielectric 151separates the gate electrode 155 from the SiC semiconductor body 100.The gate dielectric 151 can comprise a semiconductor dielectric, forexample a thermally grown or deposited semiconductor oxide, e.g. siliconoxide, a semiconductor nitride, for example a deposited or thermallygrown silicon nitride, a semiconductor oxynitride, for example a siliconoxynitride, some other deposited dielectric material or an arbitrarycombination of the materials mentioned. The layer thickness of the gatedielectric 151 can be chosen such that a threshold voltage of thetransistor cells TC lies in a range of from 1 V to 8 V or between 3 Vand 6 V.

The gate structures 150 can exclusively comprise the gate electrode 155and the gate dielectric 151 or, in addition to the gate electrode 155and the gate dielectric 151, can comprise further conductive and/ordielectric structures, e.g. compensation structures, field plates orisolating dielectrics.

In the mesa sections 190, source regions 110 are formed towards thefront side of the SiC semiconductor body 100, which source regions candirectly adjoin the first surface 101 and both mesa sidewalls 191, 192at the longitudinal sides of the respective mesa section 190. In thiscase, each mesa section 190 can comprise a source region 110 havingsections connected to one another in the SiC semiconductor body 100 orhaving at least two sections separated from one another in the SiCsemiconductor body 100 on mutually opposite sides of the mesa section190 which are connected to one another with low impedance via a contactor trench contact adjoining the mesa section 190.

The mesa sections 190 furthermore comprise body regions 120, whichseparate at least sections of the source regions 110 from the driftstructure 130, and form first pn junctions pn1 with the drift structure130 and second pn junctions pn2 with the source regions 110. The bodyregions 120 directly adjoin at least the first mesa sidewall 191. Avertical extent of the body regions 120 corresponds to a channel lengthof the transistors cells TC and can lie in a range of from 200 nm to2500 nm or in a range of from 400 nm to 1000 nm. Both the source regions110 and the body regions 120 are electrically connected to a first loadelectrode 310 on the front side of the SiC semiconductor body 100.

The first load electrode 310 can form a first load terminal L1, whichcan be an anode terminal of an MCD, a source terminal of a power MOSFET,of some other IGFET, or an emitter terminal of an IGBT, or can beelectrically connected or coupled to the first load terminal L1. Thesecond load electrode 320 on the rear side can form a second loadterminal L2, which can be a cathode terminal of an MCD, a drain terminalof a power MOSFET, of some other IGFET, or a collector terminal of anIGBT, or be electrically connected or coupled to the second loadterminal L2.

Diode regions 160 can be formed between the body regions 120 and thesecond mesa sidewalls 192, wherein a maximum dopant concentration in thediode regions 160 along the second mesa sidewalls 192 is higher, e.g. atleast two times or even also ten times higher, than a dopantconcentration in the body regions 120 along the first mesa sidewalls191.

In accordance with one embodiment, the transistor cells TC are n-channelFET cells having p-doped body regions 120, n-doped source regions 110and an n-doped drift zone 131. In accordance with another embodiment,the transistor cells TC are p-channel FET cells having n-doped bodyregions 120, p-doped source regions 110 and a p-doped drift zone 131.

A load current that flows through the SiC semiconductor body 100 betweenthe first and second load electrodes 310, 320 in the on state of thesemiconductor component 500 passes through the body regions 120 as acharge carrier flow in inversion channels induced along the gatedielectric 151. The higher dopant concentration in the diode regions 160in comparison with the dopant concentration in the body regions 120 canprevent the formation of inversion channels along the second mesasidewalls 192, protect the gate dielectric 151 at the bottom of the gatestructures 150 against degradation and/or connect the diode regions 160to the first load electrode 310 with low impedance.

The diode regions 160 extend e.g. as far as a contact formed at thefirst surface 101 or as far as a trench contact extending from the firstsurface 101 into the respective mesa section 190 and are electricallyconnected or coupled to the first load electrode 310. The diode regions160 can vertically overlap the gate structures 150, wherein sections ofthe diode regions 160 are formed in the vertical projection of the gatestructures 150. A maximum concentration in the diode regions 160 ishigher than a maximum concentration in the body regions 120.

In the body regions 120, the maximum dopant concentration can be closebeneath the first surface 101. In the diode regions 160, the dopantconcentration can also have, besides an absolute maximum (i.e. globalmaximum relative to the respective diode region 160) near the firstsurface 101, a local maximum in the deepest region relative to the firstsurface 101 and below a lower edge of the gate structures 150. In an offstate of the semiconductor component 500, the sections of the dioderegions 160 below the gate structures 150 can shield critical regions ofthe gate dielectric 151 against a high electric field at the first pnjunction pn1. A distance between opposite edges of adjacent dioderegions 160 can lie in a range of from 300 nm to 5 μm, for example in arange of from 500 nm to 2 μm.

The diode regions 160 form third pn junctions pn3 with the driftstructure 130. The first and third pn junctions pn1 and pn3 formsections of an intrinsic body diode.

Zones 133 of the conductivity type of the drift zone 131 are formedbetween the diode regions 160 and the drift zone 131 and, in theexemplary embodiment shown, in each case directly adjoin the dioderegions 160 but, in accordance with other embodiments, can also bespaced apart from the diode regions 160 slightly, for example by lessthan 1 μm. A horizontal extent of the zones 133 can be less than, equalto or greater than the horizontal extent of the diode regions 160. Avertical extent Δx of the zones 133 can be at least approximately 50 nmand maximal approximately 1 μm. In this exemplary embodiment, the zones133 are spaced apart from the drain-side end of the channel bothlaterally and vertically and reduce the anode emitter efficiency of theintrinsic body diode in the region of the third pn junctions pn3.

FIG. 3A shows a semiconductor component 500 comprising planar gatestructures 150 on the front side of a SiC semiconductor body 100,wherein an individual gate structure 150 is assigned to two transistorcells TC formed symmetrically with respect to the gate structure 150.

The gate structures 150 in each case comprise a conductive gateelectrode 155 and a gate dielectric 151, which is formed directly on thefirst surface 101 and separates the gate electrode 155 from the SiCsemiconductor body 100. A body region 120 extending from a first surface101 into the SiC semiconductor body 100 is assigned to two adjacenttransistor cells TC of two adjacent gate structures 150. Source regions110 of the two transistor cells TC extend from the first surface 101into the body region 120 having a contact region 128. The contact region128 can have a higher dopant concentration than a main part of the bodyregion 120 outside the contact region 128. It is moreover possible forthe contact region 128 to adjoin the first surface 101 between thesource regions 110.

A drift structure 130 having a drift zone 131 and a contact layer 139separates the transistor cells TC from a second surface 102 of the SiCsemiconductor body 100, wherein the drift zone 131 can extend to thefirst surface 101 between adjacent body regions 120. A second loadelectrode 320 directly adjoins the second surface 102.

In the on state, the transistor cells TC, in channel regions of the bodyregions 120, form lateral inversion channels along the first surface 101between the source regions 110 and the sections of the drift zone 131that adjoin the first surface 101.

An interlayer dielectric 210 separates the gate electrode 155 from afirst load electrode 310 on the front side of the SiC semiconductor body100. Contacts 315 in openings of the interlayer dielectric 210 connectthe first load electrode 310 to the contact regions 128 and the sourceregions 110.

Zones 133 which are spaced apart at least vertically from the gatestructures 150 and in particular from the channel ends of the transistorcells TC are formed between the body regions 120 and the drift zone 131.The zones 133 can directly adjoin the body regions 120 or be spacedapart from the latter by at most 1 μm in the vertical direction. Avertical extent Δx of the zones 133 is at least approximately 50 nm andat most approximately 1 μm.

A horizontal extent of the zone 133 can correspond approximately to thehorizontal extent of the body regions 120 or be larger or smaller. Inaccordance with one embodiment, instead of a plurality of zones 133separated from one another, it is possible to form a single, continuouszone 133 extending continuously in a lateral direction over a pluralityor all of the transistor cells TC of a cell array region.

In FIG. 3B, the gate structures 150 are formed in trenches having av-shaped vertical cross-sectional area. The gate electrode 155 extendswith an approximately uniform layer thickness along the sidewalls andthe bottom of the trenches. Mesa sections 190 of the SiC semiconductorbody 100 between adjacent gate structures 150 comprise source regions110 formed along the first surface 101 and also body regions 120 betweenthe source regions 110 and the drift structure 130.

Zones 133 of the conductivity type of the source regions 110 are formedbetween the body regions 120 and the drift zone 131 and are spaced apartlaterally from the gate structures 150 and the channel ends of thetransistor cells TC.

The semiconductor component 500 in FIG. 3C comprises gate structures 150extending from a first surface 101 into a SiC semiconductor body 100,wherein the sidewalls of the gate structures 150 extend vertically withrespect to the first surface 101. Body regions 120 are formed in mesasections 190 of the SiC semiconductor body 100 between adjacent gatestructures 150 and form first pn junctions pn1 with a drift structure130 and second pn junctions pn2 with source regions 110 formed along thefirst surface 101.

An interlayer dielectric 210 separates a gate electrode 155 of the gatestructures 150 from a first load electrode 310. Between adjacent gatestructures 150, trench contacts 316 extend from the first load electrode310 into the mesa sections 190, laterally contact the SiC semiconductorbody 100 and connect the source regions 110 to the first load electrode310. A vertical extent of a section of the trench contacts in the SiCsemiconductor body 100 can approximately correspond to the verticalextent of the gate structures 150.

Diode regions 160 are formed below the trench contacts 316, which dioderegions can be laterally adjacent to the body regions 120 and areconnected to the trench contact 316 via a more highly doped diodecontact region 169. A lateral extent of the diode regions 150 can begreater than a corresponding lateral extent of the trench contacts 316.The diode regions 160 form doped semiconductor regions of theconductivity type of the body regions 120, can extend along thesidewalls of the trench contacts 316 as far as the source regions 110and form third pn junctions pn3 with the drift structure 130.

Zones 133 of the conductivity type of the drift zone 131 and having adopant concentration that is at least double the magnitude of an averagedopant concentration in the drift zone 131 are formed between the dioderegions 160 and the drift zone 131. The zones 133 are spaced apart bothvertically and laterally from the gate structures 150 and the channelends of the transistor cells TC.

In FIG. 4, the semiconductor component 500 is a MOSFET based on a SiCsemiconductor body 100 having gate structures 150 formed in trenches asdescribed in FIGS. 2A to 2B, wherein the first load electrode 310 isconnected to a source terminal S and the second load electrode 320 isconnected to a drain terminal D.

An interlayer dielectric 210 composed of one or more layers above thegate structures 150 covers the gate electrode 155. The interlayerdielectric 210 can for example comprise a layer of thermal siliconoxide, of deposited silicon oxide, silicon nitride, silicon oxynitrideor a glass, for example BSG (boron silicate glass), PSG (phosphorussilicate glass), PBSG (boron phosphorus silicate glass), FSG (fluorinesilicate glass) or a spin-on glass or consist of such a layer. Contacts315 extend through openings in the interlayer dielectric 210 and connecta first load electrode 310 bearing on the interlayer dielectric 210 tothe source regions 110 and the body regions 120. On the rear side of thecomponent, a second load electrode 320 contacts the second surface 102with the contact layer 139.

Along the active sidewalls of the trench structures 150 the sourceregions 110 can in each case be directly adjacent to the trenchstructure 150 and be formed exclusively between the body region 120 andthe first surface 101. In accordance with the embodiment illustrated,the source regions 110, besides a first section 111 along the activesidewalls, also comprise one or more second sections 112 which adjoininactive sidewalls of the trench structures 150 and are formed in eachcase between diode region 160 and first surface 101. In thesemiconductor body 110, the second sections 112 can for example beseparated from the first sections 111 by the diode region 160 and/or thebody region 120 or be connected to the first sections 111 via furthersections of the same conductivity type.

The first load electrode 310, the second load electrode 320 and/or thecontacts 315 can comprise aluminium (Al), copper (Cu) or alloys ofaluminium and/or copper such as, for instance AlSi, AlCu or AlSiCu asmain constituent. In accordance with other embodiments, at least one ofthe two load electrodes 310, 320 can contain nickel (Ni), titanium (Ti),tungsten (W), tantalum (Ta), vanadium (V), silver (Ag), gold (Au), tin(Sn), platinum (Pt) and/or palladium (Pd) as main constituent(s). Atleast one of the two load electrodes 310, 320 can comprise two or morepartial layers, wherein each partial layer can contain Ni, Ti, V, Ag,Au, W, Sn, Pt and/or Pd as main constituent(s), e.g. a silicide, anitride and/or an alloy. By way of example, the contacts 315 cancomprise an interface layer 311 composed of a metal silicide, forexample, and a main layer 312 composed of the material of the first loadelectrode 310, wherein the interface layer 311 adjoins the SiCsemiconductor body 100 and separates the main layer 312 from the SiCsemiconductor body 100.

The drift structure 130 comprises current distribution zones 137 of theconductivity type of the drift zone 131 between the body regions 120 andthe drift zone 131. An average dopant concentration in the currentdistribution zones 137 is at least two times, for example at least tentimes, the magnitude of an average dopant concentration in the driftzone 131. The reduced lateral ohmic resistance in the currentdistribution zones 137 spreads the charge carrier flow through the bodyregions 120 along the horizontal directions, such that even forcomparatively low dopant concentrations in the drift zone 131 a largelyuniform current distribution is established in the drift zone 131. Thecurrent distribution zones 137 directly adjoin the channel ends of thetransistor cells TC.

The zone 133 is spaced apart from the gate structures 150 and thus alsofrom the channel ends of the transistor cells TC. A vertical extent Δxof the zone 133 is at least 50 nm and at most 1000 nm, for example atleast 100 nm and at most 500 nm. An average net dopant concentration n2in the zone 133 is higher than an average net dopant concentration n1 inthe current distribution zone 137 and higher than an average net dopantconcentration n⁻ in the drift zone 131. The zone 133 can directly adjointhe diode regions 160 or be spaced apart from the diode regions 160 inthe vertical direction, such that a first vertical section of the driftzone 131 separates the zone 133 from the diode regions 160.

The zone 133 extends continuously in a lateral direction over aplurality of adjacent transistor cells TC, for example over all thetransistor cells TC of a cell array region enclosed by an edgetermination region without transistor cells.

In FIG. 5, the diode regions 160 in each case comprise a first partialregion 161 having a maximum of the dopant concentration near the firstsurface 101 and also a second partial region 162 having a local maximumof the dopant concentration in a region below the gate structures 150,wherein the first partial region 161 separates the second partial region162 from the first surface 101. It is possible for the dopantconcentration of a diode region 160 overall to have a local maximum inthe second partial region 162 and/or to have a global maximum (relativeto the respective diode region 160) in the first partial region 161 andbetween the local maximum and the first surface 101.

The first partial region 161 laterally adjoins the source region 110 andthe body region 120 in the same mesa section 190 and also the inactivesidewall of the adjacent gate structure 150. The first partial region161 can moreover also extend along a part of the bottom of the gatestructure 150. The second partial region 162 separates the first partialregion 161 laterally and vertically from the drift structure 130.

A maximum dopant concentration p2 in the second partial regions 162 ofthe diode regions 160 is lower than a maximum dopant concentration p⁺ inthe first partial regions 161 and can be higher than in the body regions120. The maximum dopant concentration p⁺ in the first partial regions161 can be at least double, e.g. at least ten times, the maximum dopantconcentration p2 in the second partial regions 162.

The zone 133 can directly adjoin the lower edge of the second partialregions 162 of the diode regions 160 and in this case extend in alateral direction over a plurality of transistor cells TC, for exampleover all the transistor cells TC of a cell array region. Between thezone 133 and the drift zone 131, the drift structure 130 can comprise acurrent distribution layer 1371 having a dopant concentration which canbe of a magnitude approximately equal to that in the currentdistribution zone 137.

FIGS. 6A and 6B show horizontal cross sections through the SiCsemiconductor bodies 100 of two semiconductor components 500,respectively in a first horizontal plane intersecting the gatestructures 150, and in a second horizontal plane intersecting thezone(s) 133.

The semiconductor components 500 in each case comprise a cell arrayregion 610 and an edge termination region 690, which partly orcompletely encloses the cell array region 610 and separates it from aside surface 103 of the SiC semiconductor body 100 that connects thefirst and second surfaces 101, 102. All functional transistor cells TCof the semiconductor component 500 are formed in each case within thecell array region 610. The edge termination region 690 lacks functionaltransistor cells TC. An edge termination structure that laterallyreduces an electric field can be formed in the edge termination region690.

FIG. 6A shows a zone 133 extending at least over a large portion of thecell array region 610. The zone 133 can extend on all four sides of thecell array region 610 into an inner partial region of the edgetermination region 690 or can be completely absent in the edgetermination region 690. Thus, a loss of one-dimensional blockingcapability in the cell array region 610 that is possibly attributable tothe zone 133 can be smaller than a loss of blocking capability that iscaused by the edge termination.

FIG. 6B shows a semiconductor component 500 comprising strip-liketransistor cells TC formed along strip-like gate structures 150 arrangedin trenches. The semiconductor component 500 comprises a plurality ofmutually separated zones 133 which are formed substantially parallel toone another and in a manner partly overlapping the gate structures 150,wherein the zones 133 are structured in accordance with the pattern ofthe transistor cells TC.

In FIG. 7, the characteristic curve 703 shows the rise of the forwardvoltage U_(FD) as the temperature rises for a semiconductor componentcomprising a continuous zone 133 and comprising diode regions 160 inaccordance with FIG. 5, wherein the dopants in the zone 133 comprisethose having a deep energy level in the band gap, for examplephosphorus, chromium and/or iridium. Between adjacent diode regions 160,the dopants having a deep energy level reduce the emitter efficiency asthe temperature rises, with the result that the rise in the forwardvoltage U_(FD) with temperature turns out to be flatter than in the caseof a hypothetical, otherwise identical reference component without azone, for which the characteristic curve 702 shows the steeper rise inthe forward voltage U_(FD) as the temperature rises.

In the semiconductor component 500 in FIGS. 8A and 8B, the diode region160 comprises sections 1611, 1612 having dopant concentrations ofvarying magnitude, said sections being arranged alternately along alongitudinal direction of the gate structures 150. In the exemplaryembodiment shown, the first partial region 161 of the diode region 160comprises a highly doped first section 1611, which comprises acontinuous lower partial section and a multiplicity of upper partialsections that alternate with weakly doped second sections 1612 along thelongitudinal axis of the mesa sections 190. Thus, at least the firstpartial regions 161 of the diode regions 160 have only comparativelynarrow regions having a comparatively high p-type doping, which, onaccount of their small lateral extent, are activated only in the case ofa surge current and improve the surge current strength of the intrinsicbody diode. The weakly doped second sections 1612 can extend as far asthe bottom of the first partial regions 161 of the diode regions 160.Alternatively, the dopant concentration in the second partial regions162 can vary along the longitudinal direction of the gate structures150.

A longitudinal extent 11 of the highly doped first sections 1611 alongthe longitudinal direction of the gate structures 150 can beapproximately 100 nm to 1000 nm or approximately 200 nm to 500 nm. Alongitudinal extent 12 of the weakly doped second sections 1612 alongthe longitudinal direction of the gate structures 150 is at least 500 nmand at most 5000 nm.

FIG. 9A shows a semiconductor component 500 comprising a recombinationzone 135 formed between the zone 133 and the second surface 102 of theSiC semiconductor body 100. In the recombination zone 135, the densityof recombination centres is greater than in sections of the SiCsemiconductor body 100 outside the recombination zone 135. By way ofexample, within the recombination zone 135, the recombination rate is atleast double the magnitude of that outside the recombination zone 135.In accordance with one embodiment, the recombination rate in therecombination zone 135 is at least ten times the recombination rate in asection of the drift zone 131 outside the recombination zone 135. Therecombination centres comprise crystal lattice defects, heavy metalatoms, or both. The recombination zone 135 can be formed such that aspace charge zone formed during the operation of the semiconductorcomponent 500 within the absolute maximum ratings does not touch oroverlap the recombination zone 135. By way of example, at least onesection of a field stop/buffer layer 138 can be disposed upstream of therecombination zone 135 towards the first surface 101.

By way of example, the recombination zone 135 emerges from theimplantation of hydrogen, helium and/or heavier ions, e.g. argon,germanium, silicon and/or carbon, wherein the implantation produceslattice defects in the crystal of the SiC semiconductor body 100 whichare not completely annealed in subsequent heat treatments.

In accordance with another embodiment, the recombination centres in therecombination zone 135 comprise approximately positionally fixed heavymetal ions that diffuse extremely slowly in silicon carbide. Therecombination centres can be provided from a single heavy metal or fromat least two different heavy metals. Suitable heavy metals aremolybdenum, tungsten, platinum, vanadium and gold, for example.

The recombination zone 135 can form a continuous horizontal layer or canbe structured. By way of example, the recombination zone 135 can beabsent in an edge termination region or be formed exclusively orpredominantly in the edge termination region.

A vertical extent of the recombination zone 135 is at least 10 nm, forexample at least 50 nm and at most 1 μm, for example at most 500 nm. Ifcharge carriers recombine in the region of the recombination zone 135,the recombination takes place at the punctiform recombination centres.As a result of at least a large portion of the recombination eventsbeing shifted away from the crystal stacking faults and towards thepunctiform recombination centres, the growth of crystal stacking faultsin the cell array region is significantly reduced.

The recombination zone 135 is formed between the zone 133 and the secondsurface 102, for example within the drift zone 131. The recombinationzone 135 can at least partly overlap a field stop/buffer layer 138 orelse be implemented completely within the latter, wherein the fieldstop/buffer layer 138 is formed between the drift zone 131 and thecontact layer 139. The field stop/buffer layer 138 can be of theconductivity type of the drift zone 131. An average dopant concentrationin the field stop/buffer layer 138 is higher than in the drift zone 131and lower than in the contact layer 139.

FIG. 9B relates to a semiconductor component 500 comprising anadditional, further recombination zone 132, which is formed between thebody region 120 and the recombination zone 135 and is spaced apart fromthe recombination zone 135. The further recombination zone 132 can beformed near the zone 133, adjoin the zone 133 or overlap the zone 133.In the further recombination zone 132, the density of recombinationcentres is greater than in sections of the SiC semiconductor body 100outside the recombination zones 135, 132. By way of example, within thefurther recombination zone 132 the recombination rate is at least doublethe magnitude of that outside the recombination zones 135, 132. Inaccordance with one embodiment, the recombination rate in the furtherrecombination zone 132 is at least ten times the recombination rate in asection of the drift zone 131 outside the recombination zones 132, 135.The recombination centres comprise crystal lattice defects, heavy metalatoms, or both.

The recombination zones 135, 132 can be formed such that a space chargezone formed during the operation of the semiconductor component 500within the absolute maximum ratings does not touch or overlap any of therecombination zones 135, 132.

Depending on the desired blocking capability of the components, avertical extent of the drift zone 131 is at least 3 μm or at least 8 μmand a dopant concentration in the drift zone 131 is maximal 5×10¹⁶ cm⁻³.A distance Δv between the recombination zone 135 and the furtherrecombination zone 132 can be at least half or even 80% of a verticalextent Δw of the drift zone 131.

The semiconductor component 500 in FIG. 9C differs from that in FIG. 9Bby virtue of the absent zone 133.

The semiconductor components 500 shown in FIGS. 10A and 10B in each casecomprise a pn diode structure formed in a SiC semiconductor body 100.The semiconductor components 500 are for example pn diodes or suchsemiconductor components which, besides a pn diode, also comprisefurther semiconductor elements, e.g. transistors.

The SiC semiconductor bodies 100 in each case comprise a drift structure130 having a drift zone 131 of a first conductivity type, wherein anaverage dopant concentration in the drift zone 131 is at least 5×10¹⁴cm⁻³ and at most 5×10¹⁶ cm⁻³. Depending on the desired blockingcapability of the components, a vertical extent of the drift zone 131 isat least 3 μm or at least 8 μm.

Between the drift structure 130 and a first surface 101, an injectionregion 125 of a second conductivity type is formed in the SiCsemiconductor body 100 and adjoins a first surface 101 of the SiCsemiconductor body 100. A contact structure 340 at the first surface 101electrically contacts the injection region 125. The contact structure340 forms an anode terminal A or is electrically connected to an anodeterminal A.

Between the drift zone 131 and a second surface 102 of the SiCsemiconductor body 100, said second surface being situated opposite thefirst surface 101, the drift structure 130 comprises a highly dopedcontact layer 139. A rear-side contact structure 350 forms an ohmiccontact with the contact layer 139. The rear-side contact structure 350can form a cathode terminal K of the semiconductor component 500 or beelectrically connected to a cathode terminal K.

A zone 133 of the first conductivity type is formed between theinjection region 125 and a second surface 102 of the SiC semiconductorbody 100, said second surface being situated opposite the first surface101, and is electrically isolated from the contact structure 340.

In the semiconductor component 500 in FIG. 10A, the zone 133 directlyadjoins the injection region 125 of the second conductivity type and isstructured in the horizontal direction.

By contrast, FIG. 10B shows a semiconductor component 500 comprising acontinuous zone 133 spaced apart from the injection region 125, whereina distance Δz between the injection region 125 and the zone 133 is atmost 2 μm, e.g. at most of 1 μm.

For further details and embodiments of the SiC semiconductor body 100and the zone 133, reference is made to the semiconductor components 500described above. By way of example, the semiconductor components 500according to FIGS. 10A and 10B can comprise at least one recombinationzone 135 between the zone 133 and the second surface 102.

The semiconductor components 500 in FIGS. 11A and 11B in each casecomprise an MPS (merged pin Schottky) diode structure, formedpredominantly in a SiC semiconductor body 100.

The SiC semiconductor bodies 100 in each case comprise a drift structure130 having a drift zone 131 of a first conductivity type, wherein anaverage dopant concentration in the drift zone 131 is at least 10¹⁵cm⁻³. Depending on the desired blocking capability of the semiconductorcomponent 500, a vertical extent of the drift zone 131 is at least 1 μmor at least 3 μm or at least 8 μm. It is possible for the verticalextent of the drift zone 131 to be at most 40 μm or at most 20 μm.

Between the drift structure 130 and a first surface 101, a multiplicityof injection regions 125 of a second conductivity type are in each caseformed in the SiC semiconductor body 100 and adjoin a first surface 101of the SiC semiconductor body 100. A contact structure 340 at the firstsurface 101 electrically contacts both the injection regions 125 andsections of the drift zone 131 which adjoin the first surface 101between the injection regions 125, wherein the contact structure 340forms a Schottky contact SC with the drift zone 131. The contactstructure 340 forms an anode terminal A of the semiconductor component500 or is electrically connected to an anode terminal A.

Between the drift zone 131 and a second surface 102 of the SiCsemiconductor body 100, said second surface being situated opposite thefirst surface 101, the drift structure 130 comprises a highly dopedcontact layer 139. A rear-side contact structure 350 forms an ohmiccontact with the contact layer 139. The rear-side contact structure 350can form a cathode terminal K of the semiconductor component 500 or beelectrically connected to a cathode terminal K.

At least one zone 133 of the first conductivity type is formed betweenthe injection region 125 and a second surface 102 of the SiCsemiconductor body 100, said second surface being situated opposite thefirst surface 101, and is electrically isolated from the contactstructure 340.

The semiconductor component 500 in FIG. 11A comprises a multiplicity ofzones 133, each directly adjoining one of the injection regions 125,wherein a lateral extent of the zones 133 can approximately correspondto the lateral extent of the injection regions 125.

By contrast, FIG. 11B shows a semiconductor component 500 comprising acontinuous zone 133 spaced apart from the injection regions 125, whereina vertical distance Δz between the injection regions 125 and the zones133 is in each case at most 1 μm.

FIG. 12A relates to a method for producing a semiconductor component 500comprising a field effect transistor structure having transistor cellsTC, as illustrated e.g. in FIGS. 2A and 2B.

A mask layer is applied on a semiconductor substrate comprising aprecursor of a semiconductor body 100 as shown e.g. in FIGS. 2A and 2Band is structured by means of a photolithographic method, wherein animplantation mask having mask openings emerges from the mask layer. Hereand hereinafter, a “semiconductor substrate” can comprise a wafer and/oran epitaxially grown silicon carbide semiconductor body.

Dopants that define the doped semiconductor regions are introducedthrough the mask openings by means of ion implantation (902). Inaddition, dopants that define the zones are introduced through the maskopenings by means of ion implantation (904). The dopants that define thezones can be introduced before and/or after the dopants that define thesemiconductor regions.

FIG. 12B relates to a method for producing a semiconductor component 500comprising an MPS diode structure as illustrated in FIG. 11A.

A mask layer is applied on a semiconductor substrate comprising aprecursor of the semiconductor component 500 as illustrated in FIG. 11Aand is structured by means of a photolithographic method, wherein animplantation mask having mask openings emerges from the mask layer.

Dopants that define the injection regions are introduced through themask openings by means of ion implantation (912). Before or afterwards,dopants that define the zones are introduced by means of ionimplantation (914).

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat a variety of alternate and/or equivalent implementations may besubstituted for the specific embodiments shown and described withoutdeparting from the scope of the present invention. This application isintended to cover any adaptations or variations of the specificembodiments discussed herein. Therefore, it is intended that thisinvention be limited only by the claims and the equivalents thereof.

What is claimed is:
 1. A semiconductor component, comprising: a mergedPiN Schottky (MPS) diode structure in a SiC semiconductor body having adrift zone of a first conductivity type; an injection region of a secondconductivity type adjoining a first surface of the SiC semiconductorbody; a contact structure at the first surface, the contact structureforming a Schottky contact with the drift zone and electricallycontacting the injection region; and a zone of the first conductivitytype formed between the injection region and a second surface of the SiCsemiconductor body, the second surface being situated opposite the firstsurface, wherein the zone is at a maximal distance of 1 μm from theinjection region of the second conductivity type.
 2. The semiconductorcomponent of claim 1, wherein the zone is doped more highly than thedrift zone, and wherein a maximum dopant concentration in the zone isgreater than a minimum dopant concentration in the drift zone by atleast a factor of
 2. 3. The semiconductor component of claim 1, whereina vertical extent of the zone lies in a range of from 50 nm to 1000 nm.4. The semiconductor component of claim 1, wherein a dopant dose of thezone lies in a range of 5% to 20% of a breakdown charge of SiC.
 5. Thesemiconductor component of claim 1, wherein the zone at the location ofthe maximum dopant concentration is partly compensated with dopants ofthe second conductivity type.
 6. The semiconductor component of claim 1,wherein the zone is at least partly doped with a dopant having a deepenergy level with a gap of at least 150 meV with respect to the closestband edge.
 7. The semiconductor component of claim 6, wherein the dopantcomprises at least one of phosphorus, chromium and iridium.
 8. Asemiconductor component, comprising: a pn diode structure in a SiCsemiconductor body having a drift zone of a first conductivity type; aninjection region of a second conductivity type adjoining a first surfaceof the SiC semiconductor body; a contact structure at the first surface,the contact structure electrically contacting the injection region; anda zone of the first conductivity type formed between the injectionregion and a second surface of the SiC semiconductor body, the secondsurface being situated opposite the first surface, wherein the zone iselectrically isolated from the contact structure at the first surfaceand is at a maximal distance of 1 μm from the injection region of thesecond conductivity type.
 9. The semiconductor component of claim 8,wherein the zone is doped more highly than the drift zone, and wherein amaximum dopant concentration in the zone is greater than a minimumdopant concentration in the drift zone by at least a factor of
 2. 10.The semiconductor component of claim 8, wherein a vertical extent of thezone lies in a range of from 50 nm to 1000 nm.
 11. The semiconductorcomponent of claim 8, wherein a dopant dose of the zone lies in a rangeof 5% to 20% of a breakdown charge of SiC.
 12. The semiconductorcomponent of claim 8, wherein the zone at the location of the maximumdopant concentration is partly compensated with dopants of the secondconductivity type.
 13. The semiconductor component of claim 8, whereinthe zone is at least partly doped with a dopant having a deep energylevel with a gap of at least 150 meV with respect to the closest bandedge.
 14. The semiconductor component of claim 13, wherein the dopantcomprises at least one of phosphorus, chromium and iridium.
 15. Thesemiconductor component of claim 8, further comprising: a recombinationzone having recombination centres composed of lattice defects and/orheavy metal atoms, wherein the recombination zone is formed between thezone and a second surface situated opposite the first surface.
 16. Thesemiconductor component of claim 15, further comprising: a furtherrecombination zone having recombination centres composed of latticedefects and/or heavy metal atoms, wherein the further recombination zoneis formed between the first surface and the recombination zone and isspaced apart from the recombination zone.